On the Pb2HgO2Cl2 structure type: synthesis and crystal structure of a new representative, Pb2CdO2Br2, and electronic structure and chemical bonding in the whole Pb2MO2X2 (M=Cd, Hg; X=Cl, Br) family

Abstract

The fourth representative of the Pb2HgO2Cl2 structure type, a novel oxybromide with the chemical formula Pb2CdO2Br2 has been prepared via solid-state route and characterized by powder and single-crystal X-ray diffraction, and Raman and EDX spectroscopy. No analogs with M = Zn or X = I have been observed as yet, though chemical interaction takes place and some new compounds are likely to be produced. The peculiarities of chemical bonding within the Pb2MO2X2 family (M = Cd, Hg; X = Cl, Br) are analyzed by DFT calculations. Most likely, the main factor restricting the number of representatives for the Pb2HgO2Cl2 structure type is the size ratio of M2+ and X-.